This invention relates to surgical stapling apparatus, and more particularly to surgical stapling apparatus for substantially simultaneously applying a plurality of surgical fasteners to body tissue.
Surgical stapling apparatus in which a plurality of surgical fasteners are applied substantially simultaneously to produce an array of surgical fasteners are known. Typically these apparatus include a fastener holder disposed on one side of the tissue to be fastened, an anvil assembly parallel to the fastener holder on the other side of the tissue to be fastened, means for linearly translating the fastener holder and the anvil assembly toward one another so that the tissue is clamped between them, and means for driving the fasteners from the fastener holder so that the ends of the fasteners pass through the tissue and form finished fasteners as they make contact with the anvil assembly, thereby producing an array of finished fasteners in the tissue. The term "fasteners" is used herein as a generic term for metal surgical staples, the staple-shaped portion of two-part resinous surgical fasteners, and their equivalents. Similarly, the term "anvil assembly" is used herein as a generic term to include the anvil used to clinch metal surgical staples, the retainer holder and retainer member of two-part resinous surgical fasteners, and the equivalent of these elements.
In common use are apparatus in which the fastener holder and anvil assembly comprise a disposable cartridge removably mounted in or on a permanent actuator for supporting and actuating the cartridge. The cartridge is disposable after a single use. The permanent actuator is reusable in the same surgical procedure after reloading with a fresh cartridge, and is reusable in another surgical procedure after cleaning, sterilizing, and reloading. Also available are disposable surgical apparatus, in which the cartridge and actuator are preassembled, ready for use, and are then disposed of after a single use.
In the use of these apparatus it is of great importance that the fastener hoder and anvil assembly be positioned accurately and precisely in relation to each other, so that the tissue joining procedure occurs in a proper manner. In surgical stapler apparatus of the type disclosed in commonly-assigned Green U.S. Pat. No. 4,354,628, it is intended that the tissue to be stapled be enclosed completely between the stapler holder and the anvil assembly (as shown in FIG. 4 of that patent), i.e., none of the tissue extends past the end of the staple holder and anvil assembly. This permits the staple holder and anvil assembly to be positioned accurately relative to each other by means of a spacer member disclosed and claimed in that patent. There are, however, certain surgical procedures in which it is not possible to enclose the tissue to be stapled completely within the two legs of the stapler. In such circumstances the tissue extending beyond the legs of the stapler would prevent the spacer member from abutting against the anvil assembly and could result in improperly formed fasteners.
It is known, using instruments of the type shown in commonly-assigned Green U.S. Pat. No. 3,494,533, to apply the surgical fasteners to tissue where the tissue extends beyond the ends of the legs of the stapler. In such circumstances, an alignment pin either is forced through the tissue, if the tissue is sufficiently soft, or the surgeon must manually cut the tissue prior to pushing the alignment pin through the tissue. The cartridge and anvil used with instruments of the type disclosed in U.S. Pat. No. 3,494,533 are aligned parallel to each other through the parallel positioning of the legs of the instrument on which the cartridge and anvil are located.
As noted in U.S. Pat. No. 4,354,628, proper alignment between the fastener holder and anvil assembly of that patent is maintained primarily by these elements themselves, and it is desired not to rely on the instrument to provide that alignment. It is therefore an object of the instant invention to provide surgical stapling apparatus of the type shown in U.S. Pat. No. 4,354,628 in which there is provided means which ensures that the fastener holder and anvil assembly are substantially parallel to each other even when the tissue to be joined extends beyond the stapling apparatus.